Television apparatus



March 4 194'?. A. N. GoLDsMlTH 2,416,919

TELEVISION APPARATUS I Filed Dec. 16, 1944 5 Sheets-Sheet l Tlcl .1.

` ATTORN EY March 4, 194i?. A VN, GOLDsMl-[H 2,416,919

TELEVISION APPARATUS Filed Dec. 16, 1944 3 Sheets-Sheet 2 ATTORN EY A.N. GoLDsMn-H 2,416,919

TELEVISION APPARATUS Aff/TH- March 4, 194?.

WMV

Patented Mar. 4, 1947 anser UNITED STATES'PATENT AOFFICE.

2,416,919 TELEVISION APPARATUS eines N. Goldsmith, New York, N. Y.

Application December 16, 1944, Serial No. 568,458

18 Claims. (Cl. 178-5.2)

This invention is directed to color television systems and to colorphotographic systems. The invention to be disclosed sets forth as itsmajor concept that of controlling the color saturation of imagesproduced in color television or photographic systems. In particular theinvention nds primary application in connection with color televisionsystems which are of either the so-called sequential type where there isa cyclic change between the several component colors utilized to effectthe color representation, or which are of the so-called simultaneoustype Where each of the component-color images is simultaneouslyanalyzedand reproduced.

The invention to be described herein will set forth arrangements topermit the transmission, the reception, the recording and thereproduction f television images, scenes, pictures, likeness, maps, andthe like in color Where the images have any desired degree of colorsaturation. The saturation may extend over the complete range fromfull-color representation through the socalled pastel or reduced orlightened color shades to a black and white monochrome image.

The method and system to achieve the said objectives will be dependentupon an appropriate use of adjustable color filter assembly. Thesefilters may be of the disk, drum, film or similar type which arearranged to come Within the eld of view of an optical system^and therebyresolve the light forming the image intosuitable frames of fields of thecolor separation process.

- Where the color television system is one of the so-called simultaneousmulticolor type, the image forming light rays of a number correspondingto the number of selected component colors are passed simultaneously andindependently through component color filters of each chosen componentcolor. The color filters may each be of the socalled wedge or gradedtype so that in accordance with its position in the optical path theabsorption may be caused to vary from full absorption for any onecomponent color up to a complete transmission of that color, or, inother Words, the filter is clear. For the simultaneous type of colortelevision system, the several separate component color filters may bemoved in unison or associatively Within the image forming light beams tocare for changes in. illumination of the subject, as Will hereinafter bedescribed.

A color television system of the .so-called sequential multicolor typeis operated according to a somewhat analogous' principle except that thecomponent color filter reveals the light to an image receiving plane inthe several chosen component colors in sequence. Then, as will herein beshown and pointed out, by adjusting the location of the sequentiallychanging filter area With in the image forming light beam pathandrelative to the optical axis of the system the absorption of light maybe controlled and Varied from full absorption, as with a simultaneoussystem, through the pastels to a complete transmission.

For reasons of simplicity and in order to dene the invention in one ofits various forms, the arrangements herein to be described Will bereferred to in terms o tricolor operation, although it should beunderstood that the invention Will apply equally to bi-color orquadri-color principles, as Well as to systems utilizing componentprimary colors of high saturation only. In addition, the inventionherein to be described shall be understood as relating also to thosesystems using not only component primary colors of high saturation butalso key images in black and White as one component of the completeimage.

Often the key image section will also consist of a graded black andWhite filter which will operate simultaneously with the other componentcolor lilters. The graded black and White filter or a filter of a gradednature of any other color, where a color other than black and white isused as the key color, can readily be formed from a Wedge type ofdevice, as Will herein later be de-V scribed. t

In the more common forms of tricolor processes of color television orcolor photography, it has been the practice in the art to produce theinl dividual separation images of the component colors by the aid ofsuitable color lters through which the image forming light beams arecaused to pass. Color lters of this character are of relatively highsaturation and transmit, accordingly, only a limited and relativelynarrow portion of the spectrum to any appreciable extent.Illustratively,-the green filter, which may be considered as one of thecomponent colors of a tricolor system, transmits 'green light onlyeiiectively, although it transmits blue and yellow light usually to alimited extent but it transmits scarcely any violet or orange-red light.It thus be-V comes evidentl that lters of this character absorb a veryconsiderable portion of the thereon incident light. As a matter of fact,it is due to these lter characteristics primarily that the necessity forsuch greatly increased illumination of objects in color television andcolor photography is re-v quired, as compared to the correspondingilluminations which are entirely adequate for black and Whiteoperations.

by the several component color filters of the system is reduced by adecrease in the intensity and the saturation of the color laye-r at'such filters more light Will naturally reach the light respon-.-V sivesurface such .as the photoelectric surface of a television camera tubeor the photographic nlm of the photographic camera. This light will, ofcourse, Vforni the component color image, but, on the other hand, thesaturation or purity of the produced colors Will be correspondinglydiminished due to the reduction in absorption and, be cause such reducedsaturation color filters pass light effectively over a much Widerspectral range and they do not provide the `same degree ofdiscrimination between colors and for the reproduction of saturated orbright colors as do the filters having higher saturation and greaterlight absorption.

Continuing with filters having even stili lighter colored lter areas thecolor saturation of the images of the final light image is still furtherreduced with the production of the so-called pastel tints or,differently expressed, there is produced essentially a black and Whiteimage Which-is faintly tinted with colors suggestive of the moresaturated actual colors. Lastly, the individual color filters are madecompletely transparent so that there is, of course, no actual colorfiltering operation taking place and no color saturation is obtained sothat a black and White image finally results corresponding to thetransmission and reception of identical component-color images.

Where the color saturation or absorption of the various compcnentltersis gradually diminr ished to correspondto a gradual increase in thespectral transmission to both sides of the maxi mum transmission. pointit is desirable and usually necessary to increase the contrast, grad.-ation or the gamma of the individual color separation images in order toproduce a satisfactory pastel image or finally a black and white image.

It is a Well known fact that a suitable gamma for color images isapproximately unity, Whereas transmission arrangementsfor black andWhite images, which are dependent upon the lights and shades for theirsimulation of the relative brightyness of the differently colored areas,there should be more contrasty images and thus the gamma should usuallyexceed unity. Accordingly, if the saturation of the color filters isreduced it is desirable that the contrast of the corresponding imagesthat are produced shall b e increased correspondnsly- This inventionprovides so that Yii. the saturation of the component color lter islreduced and the light transmission therethrough :is increased suitablearrangements provide for changing the brightness controls in thetelevision color system or the exposure or aperture controls in colorphotographic systems. Such changes'as-the fore going usually willinvolve modlications in the exposure controls which will serve to adaptthe photosensitive surface to an appropriate linear responsecharacteristic in accordance with the increased rang-eA of illuminationor brightness falling thereon as a result of the changes in saturationof the component color filters.

This effect may be achieved by shifting the gamma response of thetransmitter system at times when filter changes are introduced so thatby variation of the amplifier response, for instance, the gamma may bevaried from unity or even slightly less than unity with full color, forexample, to a value greater than unity for black and White. matically bya uni-control arrangement between the filter position control mechanismand the amplifier in the case of television operations.

It has always been one of the difficulties experienced in connectionwith color television or color photography that sufficient illuminationto enable said color images to be piclred up or recorded under normallighting conditions in the latter portion of the afternoon or earlyportions of the morning is lacking so that the practical utility of thesystem is reduced. The present invention provides compensation for theseconditions and, to illustrate b-y Way of example, if it be desired totransmit television images or to record motion picture records in colorwhich shall y be representative of a football scene or game occurring inthe autumn and on a November after noon, it will be appreciated that abrilliantly col-` ored and satisfactory image may be produced during theearly part of the game and perhaps until as late as 4:00 oclock in theafternoon. By that time, for the assumed period of the year, the normallighting may have waned to such an extent that television pick-up withhigh satura tion filter units becomes difficult and electrical noiseincidental to the television transmission becomes troublesome. At thesame time, the

' reduced outdoor illumination on actual scene correspondingly reducesthe importance of color rendition.

Carrying the consideration still further, and with the example given,toward the end of the assumed football game and still later in theafternoon, the outdoor lighting will, in general, be far too dim toenable a satisfactory color telelvision pick-up o-r color photographicrecording to be obtained, while at the same time, the actual importanceof color change in the actual scene will have been still further greatlyreduced because the change in the intensity and color of the daylight atthat time. To effect a more satisfactory'transmission under suchcircumstances, this invention provides an arrangement whereby through amodification or an adjustment in the operation it will be possibleinitially to transmit full color images to be followed later by pastelcolo-red images due to a reduction inthe color absorption of the severalfilters of. the system and later to restrict the transmission on animage pick-up system to a black and White response. ri'he'se reductionsin the color values and the changes from fullcolor to the pastel shadesand next to the black and white would permit additional light to reachthe photosensitive or light sensitive image ren creasing lightconditions such as would occury on Changing from adark condition due toclouds,

The eifect may be obtained auto,

smoke or the like to a brilliant sunlight illumination the colorsaturation would be increased.

Even when ample light is continuously available for full colortelevision or color photography it is often desirable for aesthetic,dramatic or psychological reasons to change, alter or modify thesaturation of the component color filter, through an adjustment of thecolor taking arrangements. The' invention herein to be set forth in moredetail in what is to follow is capable of taking into account thesecircumstances and is arranged to provide for filter modification orchange under rsuch circumstances.

As another example of conditions when a change in illumination or achange between full color and black and white through any intermediateset is desirable, it will be readily recognized that because of thesomewhat psychological relationship between moods and colors, it isfrequently possible to exemplify such states merely by the color densityof the images. These factors can be exemplified by bearing in mind thata brightly colored image may, in general, evoke a cheerful, expansive orencouraging mood, while arrangements developing the pastel coloredpicture usually would produce a more limited or delicate emotionalresponse. Lastly, the black and white image, particularly of anappropriate gradation range, may produce a more somber or restrainedeffect.

Thus, the present invention if adapted to television studio or motionpicture technique is capable or" simulating changes which otherwisecould not be achieved.

It, accordingly, becomes an object of this invention to provideapparatus and means whereby variations in the color saturation is due tothe change in the availability of a required amount of light for highdelity color or where it is desired to simulate changing lightconditions or moods.

It is a further object of the invention to provide a color television ora color photographic process in which the effects of changing lightconditions as aiecting color saturation may be obtained in a suitablycontrolled and, if desired, changing cyclic manner.

It is also an object of the present invention to provide a system andmeans whereby simultaneous multicolor television or color photographicmethods may be effected with changes in the color saturation of thelight image influencing the light sensitive apparatus or elements.

A still further object of the invention will be found to involve the useof manual or automatic controls of the color saturation in colortelevision or colo-r photographic apparatus throughout the range betweenthe deepest colors of the selected components for providing accuratemulticolor relations and a transition to complete black and white formonochrome operation.

A further object of the invention is that of providing a system whereineither automatic or manual controls of the contrast of the componentcolor separation images may be achieved so that the individualmulticolor images are appropriately l varied throughout the transitionperiod from full color to monochrome operation in either direction.

A further object of the invention is to provide either for the automaticor manual control of the brightness of the component color separationsduring any transition change and to have the brightness control unitrelated to the contrast control.

A further object of the invention is to provide a' system wherein colorfilters in receiver units will effectively be automatically removed attime periods when monochrome images are transmitted by reason of theinsertion of a transparency in the image forming light beam path in thescanning operation.

A further object of the invention is that of providing a color balancinglter unit in combination with color separation units of saturationsvarying from full color to practically a complete transparency formonochrome transmission. The color balance lter will correctautomatically for variances in response of the light sensitive mediumupon which the impinging light rays impinge to form an image.

A further object of the invention is that of providing suitablecomplementary filter units which shall operate jointly with the mainfilter units and the color balancing lter unit, if used, to effect alinearity of operation and response from the photosensitive or lightresponsive image receiving area so that the effect of illuminationvariances may uniformly be controlled. Y

A further object of the invention is that of providing suitablecomponent color separation units in the form of disks, drums, ilexiblestrips, slides or the like to distinguish between the different selectedcomponent colors for the multicolor operation and to provide meanswhereby these units may be adjusted relative to an optical system toachieve the foregoing objects.

Other objects of the invention are those of providing a simplifiedadjustment means to shift the lter unit relative to the optical axis tothe system thereby to provide changes in the light absorption of thelter area included in the optical path.

Other objectsl are those of providing a color saturation control systemfor television or photographic use which is relatively simple in itsarrangement, which is highly effective in its operation and which isreadily adaptable to use without considerable modifications in presentlyexisting forms of such apparatus.

Other objects and advantages of the invention will, of course, becomeapparent and at 'once suggest themselves to those skilled in the art towhich the invention is directed when the following specication andclaims are read in connection with the accompanying drawings, wherein:

Fig. 1 exemplifies one form of color saturation control systemparticularly adapted for a television use;

Fig. 2 is a modification of the arrangement of Fig. 1 wherein a filterdrum unit is used to replace the filter disk unit of Fig. 1;

Fig. 3 is a still further modification of the arrangement of Fig. 1utilizing three separate control lter units from which the severalselected component colors are derived;

Figs. 4 and 5 show two different forms for thel :filter disk sections ofthe arrangement of Fig. 1 in which Fig. 4 provides a filter with amaximum color absorption toward the outer edge with a transparency onits inner edge arrangement and the arrangement of Fig. 5 provides formaximum color absorption on the inner edge of the filter disk and aminimum absorption or full light transmission along the outer edge ofthe disk, and,

Figs. 6 and 7 respectively are curves to show more particularly theoperation of the system;

with Fig. 6 representing conditions' of color ablsorption where thelters vary from maximum saturation to low saturation or pastel renditionand on down to zero saturation represented by a transparency, and Fig."I diagrammatically illustrating transmissionof the lters'for differentconditions of illumination as regards the color of light'and the shiftthereof from white light (as assumed with Fig. 6) to a more reddish(orange) light, which may be regarded illustratively as being theconditions prevailing at the time of sunset or conditions present undernormal incandescent lighting.

Referring now to the drawings and first to the arrangement of Fig. 1,there is exemplified therein a tricolor sector shaped rotary disk filterH for use'in combination with either a cyclic color television or acyclic cinematographic system. rhe disk I I is composed of a pluralityof separate sections i3, i and il' with the outer edge of each sectionextending along the .periphery of the disk for about 120. vAnyequivalent or operative form of disk filter may alternatively be used,For purposes of illustratiens it may be assumed that the filter sectioni3 is green to transmit green light while the filter section I5 may beassumed to be blue-violet to transmit blue light and the iilter area orsection I'I may be assumed as being red to transmit red light. Thecomplete filter unit is supportedon a spindle or shaft I9 which, ifdesired, may have its ends supported in bearing' members (not shown)carried in the support members 2|.

For purposes ofillustration the disk may be assumed to be driven'bymeans of a motor 23 which is preferably so arranged that it drives thespindle I9 either directly or through a suitable gearing or other drivearrangement (not shown). Where the motor drives the spindle i9 directly,the spindle may form a part of the motor rotor, so that if it be desiredthat the system shall transmit color television images or produce colormotion picture films at a rate of twenty-four lms per second, thedriving motor 23 may be driven at a speed of 1440 R. P. M. The motor 23may be supported in any desired manner but preferably is attached to aVsuitable base member 25 which, in turn, is secured to the uprightsupport member 2I. Provision is made for so driving the motor as torelate the driving speed to the deflection frequency and among thevarious ways that this effect may be .achieved reference may be madepurely .by Way of example to Bedford 1Batent No. 2,137,010, grantedNovember 15, 1938, wherein there is disclosed a system which willcontrol the frequency of 'an electron impulse generator circuit withrespect to the frequency of a current iiowing in a power line utilizedfor driving a motor operating in conjunction with'a suitable rotaryelement in order that an interlock between the rotational or deflectionfrequency and the power supply frequency may be achieved. Itis, ofcourse, to be understood that other means may be utilized as desired,and the reference to tlie Bedford patent is purely by way of example.

In an arrangement of the character `herein disclosed, it will also beassumed for purposes of reference that light from animage (not shown) isdirected along the path indicated by the arrow 21 to pass through thecomponent color separation lter disk unit il and the optical system 29to reach either a light sensitiveelement, surface or electrode of atelevision camera tube 45 or the light sensitive motion picture lm of amotion picture device. In either case, the optical system 29 may be ofany suitable character which is so arranged to direct the light raysthat vpass through the vcomponent color lter disk II as to form an imagethereof on a suitable camera tube Aor other light-l sensitive surfacesor to form the image upon a photographic nlm.

As the disk I i rotates in the direction indicated by the arrow,different color component sections progressively intersect the opticalaxis of the lens system and thus regulate thereby the co-lor of thelight which passes through the optical system 29 to form an image uponeither the light responsive arrangement of the camera tube (not shown)or the iilm of the photographic camera device (not shown). Wheretelevision operations are concerned, the camera tube scanning operationsto produce the television signals are carried forward in known manner.

Therev may be interposed between the filter disk unit II and the opticalsystem 29 a color compensating or balancing filter arrangement 3|.rI'his lter unit 3l is'of such character as to correct thenon-uniformity of response of either the camera tube in the televisionsystem or the photographic film in a photographic system, since it hasbeen known for some time that neither photoelectric surface of thecamera tube nor the film emulsion surface of the photographie filmusually respond equally to all colors of light in that their response isnot normally completely panchromatic.

A color filter to provide the color balance or compensation is disclosedin more detail by my copending patent application, Serial No. 512,119,filed November 29, 1943, in which a color balancing iilter has been setforth, and particularly so in connection with its use in combinationwith the component color separation iilter, the optical system and thelight responsive target of a television camera tube or a photographicfilm emulsion. It is, therefore, to be understood that the presentdisclosure contemplates the inclusion of such a color balancing filter,where desired, and, particularly so, when areas of maximum lightabsorption are interposed in the optical path. In any event it is to beunderstood that any motion of the color balancing nlter relative toother elements shall be such that the color balancing filter remainsstationary during any one cycle of use of the component color separationfilter and the color balancing lter includes usually lo-w saturation orlow light absorption sections of the selected color components,including white, Where desired, in order that by adjustment of the areaof each of the cc-lor balancing filter sections which encompass theoptical path, a correction in the light values of thecomponent-colorimages shall be applied.

The end support elements 2i of the motor and filter assemblies aresupported from a main base member 33 which is arranged in the form ofthe system as herein illustrated by Way of example so as to be capableof motion in a vertical or transverse plane relative to the opticalsystem 29. rlhe directions of motion in the up and down or transversedirectionsare indicated by the arrows adjacent the base member 33. Thesupport elements or rods 35 and 31, for instance, carry the completeassembly heretofore described. These rods are arranged so as to beadapted to move upwardly and downwardly through the control of anydesired form of mechanical linkage. In one form, for example, thesupport elements 35 and 31 will be assumed to terminate in rack sectionswith which suitable pinions may be arranged to mesh so that by turningthe pinion an upward or downward motion of the assembly may be effected.The complete operational form which has been above disclosed is such'that' with the lter arrangement oi the assembly in Aits lower positionwill exhibit the'deepestcolor saturation lter sections transverse to theoptical path or axis through the lens system 2S. This, for instance,might represent conditions of transmission for maximum lighting as wouldbe represented,.for instance, between the highest intensity studiolighting o1' for the most brilliant daylight conditions. By way or anindication of these conditions and for a guide in adjusting the disk il,a pointer 39 may be attached to the support base member 33 so as to moveupwardly and down wardly therewith relative to a scale 4l. The pointer39 in its lowermost position relative to the scale di will then indicatethat the filter or component color separation disk Il is being utilizedunder conditions of the most brilliant light, whereas its uppermostposition relative to scale il! will indicate that the complete assemblyhas been elevated with regard to `an assumed photographic optical system29 so that the color areas of minimum lter density of the componentcolor separation disk il areincluded in the optical path. This latterposition thus would represent conditions of dim light and colorabsorption would be at a minimum o-r Iapproach at least a transparencywhich would represent black and white.

It is evident from what has been stated above that ii the position ofthe color separation disk i l is varied relative to the optical axis ofthe system, provision should be made to control the contrast orbrightness control in the transmitter unit or ampliiier where the deviceis being used for color television transmission. This may be done bysetting or varying the gain of the amplifier appropriately in accordanoewith the light intensity projected through the optical system 29.

control is so arranged that the contrast of the image for transmissionis progressively increased with reductions in brightness of the im- Thecontrol element 43 may be considered as being pivotally attached to alever element 44 which may have its fulcrum at point 46, and so linkedand arranged as to vary the gamma control element (not specificallyshown) contained within the control unit and amplifier 48. Video orimage signals representing the output from the camera tube l5 areappropriately amplied, the blanking and sync signals are added, and theD. C. components reinserted in a conventionally known manner in a unitherein illustrated for convenience as the amplier 50. The output of sucha unit 5b' is then fed into the gamma control unit [i8 which may be cithe type shown and described particularly by U. S. Patent No. 2,326,907,for instance, which was granted to K. R. Wendt on August 17, 1943. Thecontrol'lever element ifi which turns about the pivot point 46, as abovestated, may then be assumed to be connected to vary a suitable resistorin the gamma control unit and ampli-iler '38 to set the gamma fortransmission in accordance with the color density of the lter areaswhich are included in the optical path. To effect such a control of thegamma, for instance, it will be understood that the variation willresult by the motion of lever 44 varying a resistor (not shown) whichwould correspond to resistor 61 which is illustrated by Fig. 4 of theabove mentioned Wendt Patent No. 2,326,907.

Output signals to energize a transmitter or any other communicationchannel may be derived in any known manner, for example, as also shownby the same Wendt patent.

Reference may now be made to Fig. 2 of the drawings wherein it will beseen that a modication of the .arrangement of Fig. 1 has beenillustrated. Again, as in Fig. 1, the image forming light beams areprojected along a path 21 (the optical axis, for instance) through theappropriate color iilter and thence, through an optical system,conventionally represented at 29, to fall upon the light sensitivemosaic of the television camera tube it or a photographic nlm containedwithin a motion picture camera or even the film contained within a stillcamera. As in the arrangement of Fig. l, the color filter unitinterposed in the image forming light beam path serves to presentdiiierent color filter areas in a cyclic or sequential order within theoptical path so that different color lights are presented to the lightsensitive surface upon which the image is formed. The arrangement ofFig. 2 provides a modification in that use is made of a color lter drumunit :l1 which will replace the color disk light iilter unit li ofFig. 1. The color filter drum unit 41 comprises a plurality of surfacesformed as light lters. These filter areas are the surfaces l5 adapted totransmit the red image, the surface l1 for transmitting the blue image,and the surface i3 for transmitting the green image.

The complete drum assembly, as shown, is arranged to turn upon a supportspindle or drive shaft 'i9 which is carried inan appropriate bearingmember 5|. The drive shaft 49 is turned by a motor 23 which is carriedupon a support base t3 and the rotor element of the motor turns themotor shaft which is arranged through appro-l priate gearing (notshown), such as bevel gears,

, to rotate the shaft te at either the speed of the motor or at areduced or increased speed. As was explained in connection with thearrangement of Fig. 1,`the iilter sections I3, l5 and I1 are graded indensity so that the most dense iilter area, for instance, is near therim 51 of the drum 41 whereas the clearest or most nearly transparentsection of each of the lters is near the drum hub 59. Accordingly, ifthe motor 23 and its support element 53 is moved back and forth` in thedirections shown by the arrows in the support frame 6i, it is apparentthat the motor, the complete bearing assembly,and the drum 41 will allbe shifted laterally so that different density filter areas come withinthe image forming light beam path 21 to vary the color range of thelight image reaching the television camera tube 45 or thephotographicfilm where camera recordings are made in much the same manner as theraising or lowering of the support platformv 33 in Fig. l provideddifferent densities of lter in the image :forming light beam path.

' So that the conditions of lter transmission to the camera tube orphotographic lm may be measured readily, a scale 63 is indicated on thesupport 'base 5I and the indicator pointer 65 carried on the adjustableframe 53 indicates by its position on the scale the 'generalrelationship of `color lter density instantaneously interposed in thelight beam path. No arrangements have been shown, for reason ofconvenience, for moving the support base 53 relative to the supportelement il but it is to be understood that any form of crank or geardrive or even, where desired, electric motor drive arranged to becapable of reversal may be utilized. Mechanical drives of this natureare well known and readily can be set up to provide interruptedreciprocal operations so that further details need not be shown withrespect to the systems of either Fig. 1 or Fig. 2.

There may also be interposed in the image forming light beam path 21 asecond lter unit 3| which may function as a color balancing, colorcompensating lter or a diversied color lter. Arrangements of this typehave already been explained in connection with the showing of Fig. 1 andsuch a filter may or may not be used as desired. The color balancingfilter, as already stated, is disclosed and claimed in detail in thecopending patent application, Serial No. 512,119,

above referred to.

The arrangement of Fig. 3 shows in a most conventional manner theadaptation of the system to a simultaneous tricolor operation. To effecta simultaneous tricolor operation the image forming light beam is split,in known manner, for instance, into three distinct paths. Then, at somesuitable point in each of the separate light paths, the component colorseparation lilters are located so that the image forming light beamspassing along each optical path toward the photosensitive surface of thetelevision camera tube or the photographic lm of the photographic camerato form the light image thereon must pass through these lters. Thus,each formed optical image will be of a different component color.

For reasons of simplicity and because systems for effecting this form oflight beam control are known, they are not illustrated herein. However,the illustration of Fig. 3 is intended to indicate the manner in whichthe component color absorption due to the lilters in the image forminglight beam paths may be varied for each color simultaneously. It will beappreciated that there are many ways to provide the different densitylters which are conventionally represented by Fig. 3. In one form theymay be constituted as wedges with a maximum saturation at the uppermostedge and the minimum saturation at the lowest edge, or, if desired, thereverse arrangement is equally as desirable. The filter is positioned,as in the arrangement of Figs. 1 and 2, close to the objectives used forforming a light image upon the light sensitive surface of either thecamera tube or the photographic camera. Alternatively, the lter may bepositioned at any other point in the image forming light beam path solong as the image forming light beam is focused upon. the lightsensitive surface and the image forming light beam passes through arelatively small fraction of the lter area so as to enable adequatecolor asturation control to be effected.

When using the modification shown by Fig, 3, it will be assumed that theimage forming light beam has been divided or split into three distinctpaths so that the light beams which are to form the red image passthrough an optical system conventionally represented at 2BR, while thegreen image will be formed from the light rays passing through theoptical system 29G, and, likewise, the blue response will be effected byreason of the remaining light rays passing through the optical system29B. The lter units 23R, ZBG and 29B are located in the same generalrelationship with regard to each of the optical systems for effectingseparation of the red, the green and the blue images. The filters, asabove noted, are preferably of the wedge variety and arranged toencompass considerably more area than the optical system itself.

The red lter 'I5 is positioned within a support frame Tl so as to becapable of motion within the support frame in an up-and-down direction,for instance, or its equivalent, as indicated by the arrows. The lteralso may have an extension '19 provided at one end. This end ispreferably formed as a rack unit 8| so as to be capable of meshing withthe pinion 83 whereby when the pinion is turned in a clockwisedirection, for instance, the filter area 15 may move upwardly relativeto the assumed stationary optical system 2BR in order that less denselter areas shall be included in the optical path. Similarly, acounterclockwise rotation of the pinion 83 will bring a more dense lterarea within the range of the optical system 2BR. Thus., it is evidentthat a controlled rotation of the pinion 83 meshing with the rack 8| iscapable of adjusting the position of the filter 15 relative to theoptical system. f

Similarly, the green filter area 85 is positioned within a support frame8l so as to be capable of motion relative to the optical system 29G in amanner like that explained for the red illter. Here again, the greenfilter 85 is formed with one extending end 83 on which rack teeth 9| areprovided for meshing with the drive pinion 93, as explained with regardto the red filter. Lastly, the blue iilter 85, which also has its mostdense color area in the region corresponding to the dense areas offilters 'l5 and 85, is positioned to be supported within the frame ,91.This lter, like the lters 'l5 and 85 already described, has an extendingend portion 99 formed into a rack lOl which is arranged to mesh with thepinion |03 so that rotation of the pinion in a counter-clockwise or aclockwise direction will bring a less dense or a more dense filter areawithin the range of the optical system 29B.

Since it is desirable that the nlters move in unison so as to bring moredense or less dense areas within the optical paths, the several pinions83, 33 and |03 are shown as being unicontrolled, which is indicated byreason of the dot and dash lines connecting them.

For the purpose of conventionally indicating that the brightness and/ orcontrast controls used in the television transmission systems may bevaried simultaneously with a shift in the filter positions relative tothe optical systems, there has been shown conventionally a connection|05 which it will be assumed leads to the control of all of thetelevision amplifier units used with the simultaneous system. This maybe accomplished by virtue of a control of a potentiometer, for instance,which will shift the control of an appropriate discharge tube inwell-known manner or change the operating characteristics of a dischargetube in a well-known manner, andas explained in connection with Fig. 1,so that for simplicity of illustration, the complete assembly is notshown.

It will be apparent that there are many possible wedge arrangements forcolor filters which are capable of use in connection with arrangementsof the types shown by all of Figs. l, 2 and 3. The schematic showing ofFig. 4 illustrates one such form of filter. Y

It will be assumed that the lter unit of Fig. l

corresponds to one section I1, for instance, of the ilter disk ll ofFig. 1. Accordingly, the filter is capable of up-and-down motion in thedirection shown by the arrows while rotating on its drive shaft orspindle IS. With the disk portion shown, the optical system 2S isindicated as covering an area somewhat internally of the disk so that anintermediate color absorption occurs. The segmental sector of the filtershown by Fig. 4 indicates that an area Hel nearest the periphery of thedisk has maximum color absorption. There is then a gradation in densityof the lter so that at the center area Ice, for instance, there is arange of intermediate absorption and then toward the most centralportion of the disk there is an area H3 which is substantially atransparency. Itis, of course, to be understood that this is shown alsomerely by Way of. example in order to illustrate the general arrangementof the system. The actual width of any one color absorption range -is inno way critical for the effect of the colorfilter is that of the averagedensity included within the viewing aperture of the optical system 29.In connection with an arrangement of this type, it will, of course, beappreciated that where there is an area such as that shown at H3 whichis substantially a transparency, the lter unit can be utilized to eiectblack and white transmissions with the same equipment normally adaptedto color use.

The arrangement of Fig. 5 is substantially the reverse ofthat shown inFig. 4, with the main modification being that the transparency H3 nowappears at the edge of the disk whereas the most dense filter area |01is internally located on the disk while an intermediate area IBS islocated as in Fig`4 at an intermediate area. This is to illustrate thevariance permitted in the location of the different color absorbingareas. In

any event, it should be apparent that the showing of these iigures ismerely illustrative.

The curves of Figs. 6 and 7 are intended to illustrate more particularlythe operation of the system. Fig. 6 shows generally the effects oi ltershifts in position relative to they optical system for it will be seenthat the absorption of the diierent viilters blue, green and red, forinstance, vary in accordance with the saturation of that :lilter and,accordingly, in shifting from maximum saturation where full colorrendition is provided to a low saturation which will bring about atinted or pastel rendition, the absorption of the different lters mayvary within a very substantial percentage range. Lastly, Vwhen atransparent area, such as H3 or HS', is placed in the optical path, itwill be appreciated that no absorptions take place in the diierentcolors for there is no color selectivity.

The curves of Fig. 7 are intended to indicate thatwhere the light is ofone predominant color, for instance, less absorption will take place inthat color than in the other colors. kWith this condition, it may beassumed that where the light is representative of a sunset condition sothat the red and orange colors predominate, there will berelativelylittle absorption of that color light by the red lter whereasthe absorption will be greater for green and greatest for blue.Compensation for this condition is effected generally through the use ofthe color balance lter arrangements of the type hereinabove referred toin my cope'nding application, Serial No. 512,119. Under theseconditions, thecolor balancing lter will be utilized-in conjunction withthe color separation 'lter in the manner already above explained.

The foregoing description sets forth information relating to preferredforms of color separation filters, but it should beunderstood that thesesuggested forms are merely illustrative of the filter unit rather thanlimiting as regards any particular unit.

Broadly speaking, the invention, as constituted by this disclosure,should be understood as embodying `any variable density color absorbingmedium of either a solid or a liquid type or of types wherein mechanicaladjustments or the like may be made to vary the lter characteristic. Oneform of lter, in addition to those above described, which may beutilized to this end, may comprise, -for instance, a disk such as thatshown by Fig. 1 with a series of color strips arranged about theperiphery and extending inwardly from the disk edge toward the center.Such strips then may be varied systematically by increasing (or evendecreasing) the width, the closeness or the density, or all three, toeiect the results obtained with the graded type lter used as the examplein Fig.

l. If, for instance, the lter is composed of a series of uniform densitystrips or bands, these may all be of like width,w but, for instance, thecon-k centration of the strips or bands may decrease from the outer.edge of the disk inwardly toward the center so that there is a varyingproportion of color and substantially transparent media included in aplane transverse to the image forming light beam.

It will be appreciated that since the filter element in all cases islocated in a region reasonably closeto the optical element, it can beregarded as being positioned in an out of focus plane so that n o imagethereof is formed on the target area, which target area may comprise thelight sensitive element of the television camera tube or a photographichlm of a photographic device. Under such circumstances, an integratingeiect is obtained so that the eiiective :dlter density is determined inproportion to the amount of lter eleiilents instantaneously included inthe optical pat In another form, the invention maycomprise a pluralityof wedge elements which are capable .of being moved in and out relativeto each other.

In this form, the disk unit, such as that shown by Fig. l, will usuallyhave the thickest portion of the wedge toward its periphery and thethinnesty portion toward its center. Then, by means of a separateexternal holder which holds a second wedge element, e, movable wedge maybe positioned in and out so as to overlap to a greater or lesser extentthe disk wedge itself. In this way, it willY be appreciated that thewedges may be systematically varied in position relative to each otherso that by the conjoint motion of the lilter areas of all componentcolors relative to the optical path, the desired degree of colorseparation may be effected. Y

Further, with regard to the color separation,

it will be appreciated that for representations where action takes placerapidly the different component color separation filters should beincluded in the optical path in the sequential system at a ratesuiiiciently high so that image representations in the several componentcolors are produced at a rate high enough so that inv the imagereproduction, flicker effects are not apparent. Usually, the shift orchange in the saturation properties of the component color separationiilter will be eiected at a relatively l slow rate compared vto thecolor separation rate and this may be regarded as a color gradationcontrol as contrasted With the color -separation control.

Other forms of lter units may readily be adopted and these mightinclu-de, by Way of eX- ample, iilters of the liquid type where theamount of liquid included from time to time is such asto affect theresults of the disk arrangement of Fig. l, for instance. Various formsor pump apparatus to eiect this result may readily be. used in knownmanner. Thus, it is believed to be clear that With regard to theparticular type of ilter herein illustrated, wide Variances may beelected and, therefore, the invention is to be understood to reside notin the particular type 'of iilter, but in the feature of providing thecolor separation iilter of co-related density Which interposed in theimage forming light beam path to effect color separation and then, inthe motion of that stood that where reference is made throughout to atarget area, it shall be understood to mean either a iilm surface or atelevision tube target. Also, the reference to a television camera tubeand its target is to be understood as embodying either a single cameratube for effecting the result or a plurality of camera tubessimultaneously functioning in such a manner as to be particularly usefulfor simultaneous operations. In this latter instance, however, amultiplicity of camera tubes may, when appropriately scanned, effectsequential operations where all the different comu ponent colors aresimultaneously scanned on the target areas of individual tubes or targetareas in a single tube and the cyclic or sequential pro gressive changefrom one color to another is effected on all of the camera tube targetswith the signal outputs resulting from vthe scannings, the differenttarget areas then being delayed by appropriate time delay controls tocause the output signals to add together for sequential operationsV overa single channel, or the signal outputs resulting from scanning theseveral target areas may be transmitted simultaneously for all colorsover a plurality of communication channels to effect simultaneousoperation.

Thus, in these specifications where reference is made to a targetelement of a camera tube or the like, it will be understood that thetarget element may be the target element of a single camera tube or theseparate target elements of a plurality of camera tubes or, lastly, toyeffect the multicolor operations, the target element may be a singleunit formed into individual sections which each respond particularly tothe light of one component color only, and where a multiplicity ofscanning beams may scan the different sections simultaneously andcophaseally and in synchronism s o that simultaneous operations areeasily realized or the individual sections of the target may be scannedin sequence by a single scanning beam. In all instances, the electricalsignal output resulting from the scanning of the target of the cameratube is arranged to be directed through an appropriate pre-amplifier andall lother Well known associated ampliiierssuch 16 as thoseconvention-ally represented in Fig. 1, for instance, as the amplifier5D, from which the video or image signals are transferred to furtherampliers, such as the ampliiier t8, and, in most instances, are latercaused to modulate a suitable carrier frequency for transmission overcommunication channels to desired receiving points or to relaying pointsfrom which the communiw cation operations are carried forward to moreremote points.

It is, therefore, to be understood that the invention is to rbe regardedin a broad sense and insofar as possible, the claims hereinafterappended are to be understood as covering either or both simultaneousand/or sequential operations and references to target areas may includea multiplicity of target areas in separated tubes or al1 included withina single tube as well as to include the iilm target and references tocamera tube target areas similarly will include all of the target typesabove enumerated.

In the light of the foregoing disclosure, it will become apparent thatmany and various modifications maybe made in the specic structure shown.Therefore, it should be understood that the present disclosure is to beregarded as illustrative and not limiting and in such manner that allsuch modiiications may be made, provided they fall fairly within thespirit and scope of what is hereinafter claimed.

I claim:

l. In a color saturation control system wherein light raysrepresentative of an optical image are directed to form imageVrepresentations on a suitable light responsive target element, thecombination comprising a plurality of component color separation iilterelements each positioned in a non-image forming plane in the path oflight rays to the target, each of said l'llter areas having aprogressively and -predetermined]y changing color absorption ratio inthe selected component colors with the absorption ratioy Varying betweenlimits of substantially full color and substantially a transparency, andmeans to effect a conjoint variation of the co-lor separation filterlight aosorption areas effectivelyV included in said light ray Vpath foreach component color in any desired degree between substantially fullcolor and a substantial black and white.

. 2. In a color saturation control system wherein light raysrepresentative of an optical image are directed to form imagerepresentations on a suitable light responsive 4target element, thecombination comprising a component color separation lter elementincluding at least one section `of each selected coloi` Acomponent andmeans to include each lter individually in non-image forming planes inthe path of the light rays to the target area, each of said componentcolor filter areas having a progressively changing light vcolorabsorption ratio in its individual component color which varies in apredetermined manner between limits of full compo-nent color absorptionand a substantial transparency, and means to effect a conjoint variationof the color separation iilter light absorption areas included in thelight ray path to the target for each selected component color in anydesired degree between full color and a substantial black and white.

3. -In a color saturation control system for television wherein lightrays representative of an optical image are directed to formimage'representations on a suitable light responsive target element of acamera tube, the combination comprising a plurality of component colorseparation lter elements each positioned in a non-image forming plane inthe path of the light rays, each of said filter areas having aprogressively and predeterminedly changing color absorption ratio in theselected component colors with the absorption ratio varying betweenlimits of substantially full color and substantially a transparency, andmeans-to elect a conjoint variation of the color separation filter lightabsorption areas eiectively included in said path of light rays for eachcomponent color in any desired degree between substantially full colorand a substantial black and white.

Y4. lIn a color saturation control system wherein lightra'ysrepresentative of an optical image are directed along multiple paths toform image representations on suitable light responsive target areas toreceive the light, the combination comprising a component colorseparation lter element positioned in a non-image forming plane in eachof thelight ray paths, each of said lter areas having a, progressivelyand predeterminedly changing color absorption ratio in the selectedcomponent colors with the absorption ratio varying between limits ofsubstantially full color and substantially a transparency and each ofthe lters being adapted to transmit for full color substantially onlyone component color light, and means toveilect a conjoint variation ofthe color separation lter light absorption areas eiectively includedinthe `light ray path for each component colorv in any desired degreebetween substantially full color and a substantial black and white.` j

5. Ina color saturation control system for television wherein light raysrepresentative of an optical image are kdirected to form imagerepresentations on a suitable light responsive target o f a camera tubeelement which is suitably scanned to provide electrical signal outputsrepresentative of the optical image, the `combination comprising aplurality of component color separation lter'elements each positioned ina nonimage forming plane in the light ray path, each of said filterareas yhaving a progressively and predeterminedly changing colorabsorption ratio in-the selected component colors with the absorptionratio varying between limits of substantiallyl full colorandsubstantially a transparency, means to effect a conjoint variation ofthe color separation filter light absorption areas eectively includedinthelight ray path for each component color in any desired degreebetween substantially full color and asubstantial black and white, and

means operable under the control of the lterfilter section of eachselectedcolor component' and means to includeeach filter individually innon-image forming planes in the path of the light rays to the targetarea, each of said component color filter areas having a progressivelychanging light colorabsorption ratio in its individual component color.which vvaries in Ya predetermined manner'between limits offullcomponent color between full color and a substantial black and white.

7. In a television color saturation control system wherein light raysrepresentative of an optical image are directed along a, predeterminedoptical path and through appropriate optical media to form imagerepresentations on a suitable light responsive target element of atelevision camera tube so that with a scanning of the target videosignals representing the optical image are developed, the combinationcomprising a component color separation unit including at least one lterelement of each selected color component, drive means sequentially toinclude each lter element of therlter unit individually kin a non-imageforming plane in the path of the light rays to the camera tube targetarea, each of said component color i'llter areas having a progressivelychanging light color absorption ratio in its individual component colorwith the said ratio varying in a `predetermined manner,

between limits of full component color absorption and a substantialtransparency, adjustable drive positioning means to effect a conjointvariation of the color separation lter light absorption areas includedin the light ray path to the camera tube target for each selectedcomponent color in any desired degree between full color and asubstantial black and White.

8. In a television color saturation control system wherein light raysrepresentative of an optical image are directed to form imagerepresentations on a suitable light responsive target element of acamera tube, which element is scanned at a predetermined rate to produceimage signal outputs for transmission which represent the originalimage, the combination comprising a color separation lter elementincluding at least one filter section of each selected color componentand means operating to include each lter section individually,sequentially and cyclically in a non-image forming plane inthe path ofthe light rays to the camera tube target area so that the camera tube`signal outputs represent a cycliic succession of diierent componentcolor images.

each of the said component color lter sections having a progressivelychanging light color absorption ratio in its individual component colorwhich varies in a predetermined manner between limits of full componentcolor absorption andra substantial transparency, and means to eiect a-conjoint variation of the color separation lter light absorption areasincluded in the light ray path to the target for each` selectedcomponent 19 ray 'path to the camera tube and in an out of focusposition therein to provide substantially constant response from thecamera tube throughout the range of color saturation.

11. The system claimed in claim 1 comprising, in addition, a brightnesscompensating color balance filter unit also positioned in the light raypath to the camera tube and in an out of focus position therein toprovide substantially constant response from the camera tube throughoutany selected range of color saturation, and brightness control meansincluded in the light ray path to control the level of signal output forvarying color separation lter saturations so that the contrast range ofthe produced image signals is controlled and the desired gamma of theindividual component color image signal series is maintained at apredetermined value over the entire color saturation range;

`l2. A color separation filter control system for sequential forms oftricolor color responsive systems wherein light rays representative ofan optical 'image are directed through optical media to form `an opticalimage of a subject on a suitable light responsive target elementcomprising the combination of a plurality of component color separationfilter velements each located in a nonim'age forming plane transverse tothe path of the image forming light rays directed toward the lightresponsive target, `each 'of said filter areas having a progressivelyvchanging color absorption ratio in 'its individual component color withthe absorption ratio varying between limits providing substantially atransmission of one component color only and 'substantially atransparency to transmit all component colors, means to move theplurality of filters sequentially within the optical path to select theinstantaneous component color light which is directed to the target andso 'that the selected component light colors are changed at a relativelyrapid rate, and means to veffect a conjoint variation of the colorseparation filter color absorption areas'eiective in each componentcolor in any desired degree between substantially Vfull color andasubstantial black and white with the change being effected at a slowrate relative to the component color separation 'process'.

13. A color separation filter control system for sequential forms ofvtricolor color television systems wherein light rays representative ofan optical image :are directed through optical .media to form an opticalimage of a subject on a suitable light responsive target elementcomprising the combination of 'a multi-section filter unit having aplurality Yof component color separation lter elements each located in anon-image forming plane transverse to the path of the image forminglight rays directed toward 'the light responsive target, each of saidlter areas having a progressively changing'color absorption ratio ineach `of its individual component colors with lthe absorption ratiovaryingbetween limits providing substantially va transmission of lightrays of one component color only and 'substantially a transparency totransmit light of all component colors, means to move the plurality offilters sequentially within the optical path to select the instantaneouscomponent color light which is directed to the 'target and so that theselected component light colors are changed at a relatively rapid rate,and means to effect a conjoint variation of the color separation iiltercolor absorption areas effective in each .component color in any desireddegree between sub Ylight responsive target element of a televisioncamera tube comprising the combination of a multi-section lter unithaving a plurality ofV component color separation lter elements eachlocated in a non-image forming plane transverse to the path of the imageforming light .rays directed toward the light responsive target of thecamera tube, each of said filter areas having a progressively changingcolor absorption .ratio in its individual component color with theabsorption ratio varying between limits providing substantially atransmission of one component color only and substantially atransparency to transmit all component colors, means to move the lterunit within the optical path so that the individual lter elements of theplurality are cyclically and sequentially included within the opticalpath to select the instantaneous component color light which is directedAto the camera tube target and so that the transmitted selectedcomponent light colors are changed at a. rrelatively rapid rate, andmeans to effect a conjoint variation of the color separation filtercolor absorption areas effective in each component color in any desireddegree between substantially full color and a substantial black andwhite with the change being effected ata slow rate relative to thecomponent color 'separation process.

15. The system'claimed in claim 14 comprising, in addition, a brightnesscompensating color balance filter unit also positioned in thelight mypath to the camera tube and in an out of focus position therein toprovide substantially constant response from the camera tube throughoutthe range of color saturation.

16. The system claimed in claim 14 comprising, in addition, a brightnesscompensating color `balancing filter unit also positioned in the lightray path to the camera tube and in an out of yfocus posi-tion therein toprovide substantially vconstant response vfrom the vcamera tubethroughout any selected range of color saturation, `and brightnesscontrol means included 4in 'the light ray path to control the Vlevell orsignal output for varying color separation filter saturations `so thatthe contrast range of the produced image 'signals` is controlled and thedesired lgamma of the individual component color image signallseries'fls maintainedat a predetermined value lover the entire color`saturation range.

17. In a saturation control system whereln light rays representative ofan optical image are color separation -iilter flight .absorption areasfe!- fectively included in the light ray-path for each component colorin any desired between.

substantially full color and a subtantial black and white.

18. In a color separation lter control system for sequential forms oftricolor color responsive systems wherein light rays. representative ofan optical image are directed through optical media and a plurality ofcomponent color separation lter areas located in a non-image formingplane transverse to the image forming light rays so that an opticalimage of a subject is formed on a suitable light responsive targetelement comprising the steps of progressively changing the colorabsorption ratio of the filter areas in the individual component colorswith the absorption ratio varying between limits providing substantiallya transmission of one component color only and substantially atransparency to transmit all component colors, sequentially and rapidlymoving the filter areas sequentially within the optical path to selectthe instantaneous component color REFERENCES CITED The followingreferences are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 740,484 Stocoum Oct. 6, 19032,010,307 Lieshman Aug. 6, 1935

